According to a study published in the European Journal of Applied
Physiology, lowering the weight slowly may not be the best way to
increase muscle mass and strength. In that study, male and female
subjects were assigned to train for 10 weeks to either two types of
training: slow or fast velocity eccentric training. At the end of the
study, the group that trained with fast eccentric contractions had the
greatest increase in muscle hypertrophy. Muscle hypertrophy of the
type IIB fibers (i.e. type IIB fibers are fast twitch fibers)
increased from 6% to 13% in subjects. The slow group did not
experience any gain in muscle mass (1).

Farthing et al. (25) reported similar finding in that fast eccentric
lowering was superior to slow eccentric lowering. Men and women
trained the same number of reps and sets but the only difference was
the speed at which they performed the reps. The fast eccentric
lowering group increased muscle hypertrophy by 13% whereas the slow
eccentric group increased muscle hypertrophy by 7.8%.

In a follow up study by Farthing and colleagues, compared fast and
slow training, a group of 12 untrained men exercised both arms three
days per week for eight weeks (2). The men trained one arm using a
fast velocity, while they did the same number of repetitions for the
other arm at a slow velocity. At the end of the study, Type I muscle
fibers increased in size by an average of 9% with no significant
differences between fast or slow training. The change in fiber area
after training for the type II fibers was greater in the fast-trained
versus the slow-trained arm. In addition to greater increases in type
IIb fibers, the fast eccentric contractions group increased strength
to a greater extent than slow contractions.

However, incorporating plyometrics and other explosive lifts may cause
additional muscle growth of IIb fibers. For example, there have been
numerous studies that have documented increases in type IIb fibers
after explosive weight training (8, 9) and plyometrics (10, 11). For
example, when male subjects performed plyometric training for three
days a week for eight weeks resulted in significant increases in type
IIb fiber hypertrophy and peak power production. The plyometric
training consisted of vertical jumping, bounding, and depth jumping (22)

Hortobagyi et al. (20) had 15 males train either isokinetically CON or
ECC for 12 weeks. Each subject trained with 4-6 sets of 8-12 reps; 3
times a week. At the end of 12 weeks, Type I fibers did not increase
significantly in either group. The most interesting aspect of the
study was that Type II fiber area increased 10 times more in the ECC
group compared to the CON group.

1. Maximal muscle tension is developed at higher eccentric
contractions, 180° vs 30°, Farthing Chilibeck, and even much faster
with plyometrics.

2. The resistance research was isokinetics. This means

a. the eccentric effort was maximal – not just that the eccentric was
just fast – with much higher muscle tension.

b. with isokinetics resistance -- once dangerous muscle tension levels
are reached -- the neuro-muscular Golgi TO system can/does? disengage
tension. With a max eccentric weight the system somehow knows via
prroprioceptive feedback, that disengaging increases the probability
of joint injury and by passes the Golgi activity and increases tension?

Possibly this is a fast feed back, even reflex, loop, i.e., speed of
lengthening increases with tension decrease – where as disengaging
from isokinetic resistance does not increase lengthening/rotation
(about a joint) speed?

Also with the isokinetics resistance there is no resistance through
the EIC (eccentric-isometric-concentric) transition nor even the end
of the eccentric rep (or start of the concentric).

3. If it is true that fast eccentrics, 180° or more a second, does
hypertrophy IIB’s without transformation, is it because:

a. the high load fast speed eccentrics TUT (time under tension) is
short, as would be any plyometrics.

During explosive squats with weights, does anyone use a plyometric/
counter movement drop before concentric/positive movements.

The ideal resistance would overload the eccentric so that maximal
effort resulted in a speed of about 180° or more? a second. I built a
machine about 25 years ago, see US patent 4,863,161, where I combined
an inertial weight with a motor driven hydraulic system that could
overload the eccentric then release to the inertial weight already in
force. The hydraulic could be set to any speed though at the time I
wasn’t aware of the eccentric benefits/protocols.

A conversation with a hydraulics engineer from Martin Marrieta
Aerospace made me aware of the dangers associated with hydraulic
systems with multiple valves, “sometimes these systems mall function
and enormous pressures can result” so I took it off and used the
present inertial linear actuator to adjust between eccentric and
concentric. The problem was it took 1-2 seconds to translate the
inertial weight between positions losing the valuable fast EIC
(eccentric-isometric-concentric) transition speed/forces. The
technology now exists to allow this with electrical systems.

Therefore when using an inertial weight -- the athlete must use enough
to descend in about a second! Every example I’ve seen keeps eccentrics
in the 3 second per movement range. Using a power rack would be
essential. People have used detach bars in the past that drop the
weight of when the weight reached the bottom, then allows the athlete
to explode upward where the athletes training partners reattach the
weights.

This can also be done with many exercises without other means. The
most obvious example is dumbbell bench press up and let down in a
moderately wide flying motion.

There are ways to do this for any muscle(s) with any single and many
multiple joint systems. Note that pec dumbbell fly’s are a 3 joint
system.

And lastly it seems better to train this way only once every 7-10 days.

So?

The effects of eccentric and concentric training at different
velocities on muscle hypertrophy

The magnitude of maximum eccentric moments is substantially higher
than that of concentric moments (Fig. 4.7a). Since concentric moments
sharply decline with angular velocity and eccentric moments do not
decrease markedly, the difference in the magnitude between eccentric
and concentric moments becomes larger as absolute values
of angular velocity increase.The hypothesis that eccentric exercises require fewer active muscle
fibres than concentric exercises with the same resistance (Abbot et
aI. 1952; Asmussen 1953) is supported by lower values of
the ratio electromyographic activity (EMG)/force (or the slope of EMG-
force relationship) in eccentric action compared with concentric
action (Fig. 4.8a; actions appears to be similar (Fig. 4.7b; Rodgers
& Berger 1974; Komi & Viitasalo 1977; Seliger et al. 1980; Westing et
ai. 1990; however, see Enoka 1996).
Several authors have reported differences in motor unit behaviour
between eccentric and concentric actions (Nordone et al. 1989; Howell
et al. 1995; Enoka 1996): high-threshold motor units seem to be used
more extensively in eccentric actions than in concentric actions, and
the spike rate of the involved motor units is lower in eccentric
actions compared with concentric. A larger involvement of high-
threshold motor units in eccentric exercise is supported by the
observation that after intensive eccentric exercise, signs of muscle
fibre damage are seen more often in type II (fast-twitch) muscle
fibres (Friden et al. 1983), which are controlled by highthreshold
motor units.An alternative explanation for a preferential injury of
fast-twitch muscle fibres in eccentric actions is that fast-twitch
fibres may be more susceptible to stretch-induced damage because of a
less-developed endomysium compared with slow-twitch fibres (Stauber
1989).
Is eccentric action more advantageous for isometric strength training
than isometric and concentric actions because higher muscle forces
can be produced during eccentric action? In most cases, eccentric
strength training does not lead to higher isometric strength and is
comparable with isometric
and concentric training (Table 4.1). Even when
eccentric training is shown to be more effective for increasing
isometric strength, it often has sideeffects such as muscle injury
and soreness (for reviews, see Armstrong 1984; Prilutsky 1989; Friden
& Lieber 1992; see also Chapter 28). Therefore, it appears that
combining different types of exercise is a better method for strength
training. It should be noted that strength training may be action
type specific (Kellis & Baltzopoulos 1995)-eccentric training may
improve eccentric strength more than concentric (see e.g. Hortobagyi
et al. 1996b). Some studies, however, demonstrate similar
improvements in eccentric, isometric and concentric strength after
eccentric training (Kellis & Baltzopoulos 1995).

=========================

Adaptation to chronic eccentric exercise in humans: the influence
of contraction velocity.

We compared changes in muscle fibre composition and muscle strength
indices
following a 10 week
isokinetic resistance training programme consisting of fast (3.14
rad.s-1) or
slow (0.52 rad.s-1) velocity eccentric
muscle contractions. A group of 20 non-resistance trained subjects
were assigned
to a FAST (n=7),
SLOW (n=6) or non-training CONTROL (n=7) group. A unilateral training
protocol targeted the elbow flexor muscle group and consisted of 24
maximal eccentric isokinetic contractions (four sets of six
repetitions)
performed three times a week for 10 weeks. Muscle biopsy samples were
obtained from the belly of the biceps brachii. Isometric torque and
concentric and eccentric torque at 0.52 and 3.14 rad.s-1 were
examinedat 0, 5
and 10 weeks.

After 10 weeks, the FAST group demonstrated
significant [mean (SEM)] increases in eccentric [29.6 (6.4)%] and
concentric torque [27.4 (7.3)%] at 3.14 rad.s-1, isometric torque
[21.3
(4.3)%] and eccentric torque [25.2 (7.2)%] at 0.52 rad.s-1. The
percentage of type I fibres in the FAST group decreased from [53.8
(6.6)% to 39.1 (4.4)%] while type IIb fibre percentage increased from
[5.8 (1.9)% to 12.9 (3.3)%; P<0.05]. In contrast, the SLOW group did
not
experience significant changes in muscle fibre type or muscle torque.

We conclude that neuromuscular adaptations to eccentric training
stimuli
may be influenced by differences in the ability to cope with chronic
exposure to relatively fast and slow eccentric contraction velocities.
Possible mechanisms include greater cumulative damage to contractile
tissues or stress induced by slow eccentric muscle contractions.

There are indications,' however, that the fastest fibers are
preferentially recruited in the eccentric phase (Nardone et. al.
1989). The selective activation of the fastest fibers was however
most pronounced in fast eccentric actions.

===========================
Eccentric training takes place in most sports. Re training and safety it would depend on a number of factors including athlete qualification, goals, sport, bodyweight, programming and integration etc. But here are a few ideas:

*Weightlifting, skips, drop jumps.
*One could use a combination of weights + bands to enhance concentric
loading and eccentric acceleration.
*Drop and catch

Jay Schroeder seems to make use of various eccentric training methods.

"In contrast, the SLOW group did not experience significant changes in muscle fibre type or muscle torque."

Especially since we have the fact that ~5-6s negatives helped me gain enough strength to do OAC after ~6 week cycle. Granted, I'm sure a lot of it was neurological, but my muscles did grow significantly as well.

It does make sense that the highest threshold motor units are recruited when the joint angle is opening fast because they provide the most force and thus can stop the joint from opening too fast which would cause trauma to said joint. This was said in the first post (of the two above mine), and I would speculate that's because the GTO's act somewhat differently under eccentric vs. concentric contractions.... which is the difference of lengthening the muscle allows feedback to increase tension in the muscle vs. possibly autogenic inhibition. Or something like that. -_-

"In contrast, the SLOW group did not experience significant changes in muscle fibre type or muscle torque."

Especially since we have the fact that ~5-6s negatives helped me gain enough strength to do OAC after ~6 week cycle. Granted, I'm sure a lot of it was neurological, but my muscles did grow significantly as well.

It does make sense that the highest threshold motor units are recruited when the joint angle is opening fast because they provide the most force and thus can stop the joint from opening too fast which would cause trauma to said joint. This was said in the first post (of the two above mine), and I would speculate that's because the GTO's act somewhat differently under eccentric vs. concentric contractions.... which is the difference of lengthening the muscle allows feedback to increase tension in the muscle vs. possibly autogenic inhibition. Or something like that. -_-

I wonder whether weighted OAC negatives in the 1 sec range would be useful versus staying with the 5-6 sec range.

I wish I had more opportunity to experiment. Unfortunately, I don't have much time to strength train now that OCS is approaching and that my conditioning is sorely lacking.